[TowerTalk] FW: Cutting 2" Heavy Wall Cr-Mo Mast Up on Tower - RESPONSE COMPLETE

[Victor Walz]

I want to thank everyone who provided the great responses to my question.  I
am reviewing each response seriously and even considering not cutting the
mast.

 

 In summary, I received great responses that:

 

1.       Described suggested tools and cutting blades.  These responses
addressed the essence of my original posting and I received great input from
some very experienced amateurs.

2.       Important safety concerns involved in cutting the mast in place on
the 100 ft tower.  I am grateful for all this input.  This is the third time
that I have removed and installed the antenna stack on this long mast. I use
a chain fall and multiple tower plates with 1 ton eyebolts.   Success and
safety involves a well engineered installation, good planning, redundant
methods for supporting the mast, and the correct climber safety equipment.

3.       The methodology of restraining the cutoff mast.  See my previous
posting.  My intention was to cut the mast at a point inside the tower and
then lift the 100 lb. cutoff piece from above through the top bearing using
an HD gin pole.  BTW, the entire 22 ft mast was originally installed from
above through the top plate bearing using a gin pole.

4.       Questioned my decision to shorten the mast.  I didn't expect these
responses but they got me thinking.  Some responses suggested that I have
not offered a "real good reason" to cut the mast.  Maintaining the 22 ft
mast length by lowering the elevation of the rotor plate may be a good
choice.

My reason for shortening the mast was to simplify the current installation.
I removed the antennas this summer to repair the upper 20 meter 4 el yagi
which developed a problem 2 years ago.  This required first removing  the 40
meter yagi and an 80 meter rotatable dipole.  I am in my mid-sixties and do
all my tower work essentially by myself (the exception being tramming up the
larger yagis).  I started thinking out 5-10 years and concluded downsizing
may be prudent and  in order. The downside of shortening the mast is not
having a high 20 meter yagi @ 110 ft.. 

Thanks again.

Vic  N2PP

From: Victor Walz [mailto:n2pp at frontiernet.net] 
Sent: Saturday, July 26, 2014 5:41 PM
To: 'towertalk at contesting.com'
Subject: FW: Cutting 2" Heavy Wall Cr-Mo Mast Up on Tower

 

I want to clarify the current situation of the mast relative to my
methodology and safety issues.

 

The 22 ft mast has been lowered in order to remove all the antennas.  The
top of the mast is currently 4 ft above the top of the tower.

The weight of the mast is supported at three support plates and a steel
support under the bottom of the mast.  My chain hoist is also supporting the
mast.  My intention is to use my heavy duty gin pole to lift the 10 ft
section from the top of the tower once it has been cut.

 

Thanks for all the input that I have received so far.

 

Vic,  N2PP

 

From: Victor Walz [mailto:n2pp at frontiernet.net] 
Sent: Saturday, July 26, 2014 1:47 PM
To: 'towertalk at contesting.com'
Subject: Cutting 2" Heavy Wall Cr-Mo Mast Up on Tower

 

I have a 22 ft (2" OD) heavy duty Cr-Mo mast presently installed up on a 100
ft Rohn 45 tower.  It weighs 200+ pounds. I previously had a 4 el 20 meter
yagi stacked 12 ft.  above a 40 meter F12  yagi.  I just finished removing
both antennas for repairs and have decided not to reinstall the stack due to
the complexity of the installation.    I will be re-installing the 40 meter
yagi and some VHF antennas on this tower.  Consequently, I would like to
shorten the 22 ft mast by 10 ft.

 

I am looking for advice on the most efficient way to cut this very thick
high strength mast in place.  I would prefer to use battery-operated tools
such as a reciprocating saw(metal blade?) or a grinding tool (cutting
wheel?).  I can run 120 VAC (about 200 ft extension cord) up the tower if
needed.

 

What would be the optimum method for cutting this mast without excessive
tower time?  Thanks in advance for any responses.

 

Vic,  N2PP